1. Field of the Invention
This invention relates to an automatically adjustable, microcontroller controlled leak detecting apparatus and method for delivering smoke at an optimal smoke density throughout the pressure range so as to provide a reliable visual indication of the presence and location of a leak. The foregoing is accomplished by delivering a regulated supply of gas (e.g., compressed air) at an optimal pressure and flow rate from a pressure regulator to a smoke generator to be mixed with the gas and carried thereby to a fluid system under test. The leak detecting apparatus and method herein disclosed have particular application for testing systems (e.g., a turbo-charged engine of a motor vehicle) that operate at high pressures.
2. Background Art
Because of concerns for the environment, and due to excessive engine fuel consumption, it has become increasingly important to be able to test the integrity of the engine of a motor vehicle so as to determine the presence and location of a leak in need of repair. In this regard, with the engine turned off, air has been introduced into the engine system in order to attempt to hear the air leak(s). In another method, also with the engine turned off, smoke generating machines have been used for generating a visible gas or vapor that is mixed with air or other gas and carried to the system undergoing testing. By observing any smoke which exits a small and often visually imperceptible hole in the system under test, an indication is provided to the observer of the presence and location of the leak so that a repair might be made. Engine air leaks create engine loss of power and increased fuel consumption.
In the case of turbo-charged and/or boosted motor vehicles, several methods are known for locating vehicle system leaks. One such method is to use compressed air, controlled by a pressure regulator and pressure gauge, in order to introduce air pressure into the engine systems, with the engine turned off. An attempt is then made to listen for the air pressure escaping at potential leak sites that may need repair. Another method is to supply a gas under pressure (e.g., typically compressed air/shop air) to a system under test by way of a leak detector including a solenoid, a manually-operated pressure regulator, a ball indicator-type flow meter, a pressure gauge, a canister containing mineral oil, and a heater. Voltage is applied to the heater to heat the mineral oil within the canister. The oil is vaporized into smoke, and the smoke is blown by the gas supply to the test system. The visual observation of any smoke which exits the system provides a technician with an indication of the location of the leak so that a repair can be completed.
However, turbo and other boosted engine systems operate at significantly higher system pressure than non-turbo or non-boosted systems. These systems will commonly experience air leaks at high system pressures. Therefore, in the case of smoke generating leak detectors, using low pressure smoke generators cannot create sufficient pressure in the engine systems in order to simulate the engine's operating pressures. Consequently, it would be quite difficult to find leaks in such higher pressure systems using a low pressure device.
The density of the smoke being supplied to a system under test is greatly affected by the rate at which the gas flows into and out of the smoke-producing canister. A heater for vaporizing the smoke-producing solution can produce only a finite volume of smoke vapor. The volume of gas introduced into the smoke-generating canister is directly affected by the smoke generator's output pressure, such that the higher the set pressure, the greater the volume. Consequently, high pressure smoke generators produce a less-dense smoke by volume, which results in the system under test being filled primarily with the carrier gas from the initial supply thereof. In this same regard, less visible smoke exits the system making it harder for the technician to detect the leak site. When the pressure regulator is randomly increased for too long a time and/or too high a pressure setting and the system being tested is at a lower atmospheric pressure, the flow rate of the carrier gas is correspondingly increased to sometimes exceed the rate at which visible smoke can be produced. That is to say, the higher the flow rate, the thinner the smoke that will be available to exit the leak site. Consequently, the density of the smoke which exits the system is decreased which also makes it difficult for the technician to identify the leak site.
Accordingly, it would be desirable to avoid the aforementioned disadvantages inherent with a conventional manually-adjusted leak detector by automatically and simultaneously adjusting the flow rate and pressure of the carrier gas to optimal levels at which to ensure that thick dense smoke throughout the pressure range is carried to the system under test so that the leak site can be more easily and reliably determined.